INSTYTUT DENDROLOGII

Jarosław Socha, Wojciech Ochał

Dynamic site index model and trends in changes of site productivity for Alnus glutinosa (L.) Gaertn. in southern Poland

Dendrobiology 2017, vol. 77: 45-57

http://dx.doi.org/10.12657/denbio.077.004

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Abstract: 

Black alder is naturally widespread across all of Europe and has an increasing importance for forest ecosystems. Thanks to the considerable tolerance to adverse climatic and edaphic environmental conditions black alder is important both in open landscapes and can also be involved in the rehabilitation of disturbed soils. Assessment of site productivity is essential for providing a frame of reference for silvi­cultural diagnosis and prescription in order to ensure the sustainability of existing and newly established ecosystems. The most accepted method of evaluating site productivity is the site index (SI). The aim of the presented research was to develop the SI model for black alder in southern Poland. The developed SI model was used as a tool in order to test the research hypothesis assuming the increase in site productivity for black alder in southern Poland. The research material for development of SI model were stem analysis data from 180 research plots. Both, the local model parameter, which was estimated individually for every tree, and the other parameters estimated globally for the whole data set were estimated simultaneously. Changes in site productivity were analyzed on research plots and a set of 12,974 stands from the forest inventory database. Site indices calculated using the developed model are negatively correlated with age/positively correlated with establishment year of the stands. This confirms the existence of the phenomenon of increasing site productivity for black alder. During the last century site productivity measured with site index increased on average 5 m. Therefore, black alder that belongs to the fast-growing tree species should be considered of the increasing importance for forest management.

Keywords:

height growth model, height-age relationship, forest site, evaluating site productivity, alder